tests/test-simple-update.t

rebase: don't rebase obsolete commit whose successor is already rebased

This patch avoids unnecessary conflicts to resolve during rebase for the users
of changeset evolution.

This patch modifies rebase to skip obsolete commits if they are being rebased on
their successors.
It introduces a new rebase state 'revprecursor' for these revisions that are
being skipped and a new message to inform the user of what is happening.
This feature is gated behind the config flag experimental.rebaseskipobsolete

When an obsolete commit is skipped, the output is:
not rebasing 14:9ad579b4a5de "I", already in destination as 17:fc37a630c901 "K"

  $ hg init test
  $ cd test
  $ echo foo>foo
  $ hg addremove
  adding foo
  $ hg commit -m "1"

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

  $ hg clone . ../branch
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ../branch
  $ hg co
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo bar>>foo
  $ hg commit -m "2"

  $ cd ../test

  $ hg pull ../branch
  pulling from ../branch
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  (run 'hg update' to get a working copy)

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 2 changesets, 2 total revisions

  $ hg co
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cat foo
  foo
  bar

  $ hg manifest --debug
  6f4310b00b9a147241b071a60c28a650827fb03d 644   foo

update to rev 0 with a date

  $ hg upd -d foo 0
  abort: you can't specify a revision and a date
  [255]

  $ cd ..